When was the Great Wall of China build?
The practice of building fortress in northern part of China to defend against invaders was first recorded in the Spring Autumn Era in China (555 BC).
The project name was officially coined "10,000 League Wall" or Great Wall of China by Emperor Qin Shi Huang sometime around 214 BC. He connected the various fortress alone the northern China boarder build by earlier states and made it a comprehensive and connected line of defense.
Since the project's inceptions, Emperors over the years have spend a lot money and effort on maintaining and expanding the project. The current Great Wall of China as known by the world is mostly build during the 1400 by the Ming Dynasty.